DESCRIPTION: This project is a comprehensive study, using primarily genetic and molecular genetic methods, of the process of entry of phage T7 DNA into infected cells. The PI has developed an assay, based on the time of methylation of GATC sequences (that have been placed at specific locations on phage DNA) by dam methylase. Under normal conditions about 1 kb of phage DNA enters and is transcribed before the remainder of the DNA enters the cytoplasm. Both cis- and trans-acting phage mutants will be obtained to identify DNA sites and phage proteins that participate in this process. E. coli mutants, that absorb T7 but are not killed, will be isolated to identify potential host components of the system. The phage proteins that enter the cell with DNA will be identified and the initial locations of both the DNA and the proteins will be determined. Initial attempts will be made study the binding of phage proteins to the leading end of phage DNA. Other objectives are a preliminary analysis of the energetics of DNA translocation and characterization of the sequence on phage T5 that is responsible for arrest of translocation of T5 DNA.